1. Field of the Invention
The present invention generally relates to sliding mechanisms, and more particularly, to a sliding mechanism used for a sliding-type portable electronic device.
2. Discussion of the Related Art
Sliding mechanisms are widely used in sliding-type portable electronic devices, such as sliding-type mobile phones and sliding-type personal digital assistants (PDAs).
Referring to FIGS. 4 and 5, a typical sliding mechanism generally includes a main housing 70, a sliding cover 80, and a sliding module 90 positioned in the main housing 70. The main housing 70 defines two sliding grooves 77 in an inner surface of the main housing 70 and the sliding cover 80 also defines two guiding grooves 86 in an inner surface of the sliding cover 80. Each of the sliding grooves 77 includes a straight portion (not labeled) and a slanting portion (not labeled) connecting to an end of the straight portion. The sliding module 90 includes a mounting frame 92, a tension spring 94, and a pair of guiding protrusions 98. The tension spring 94 and the guiding protrusions 98 are received in the mounting frame 92. The tension spring 94 is positioned between the pair of guiding protrusions 98, with an end fixed to one guiding protrusion 98 and an opposite end fixed to the other guiding protrusion 98. Each guiding protrusion 98 includes an end inserted into one of the guiding grooves 86 of the sliding cover 80 and an opposite end inserted into one of the sliding grooves 77 of the main housing 70. Each guiding protrusion 98 is slidable in the corresponding guiding groove 86 of the sliding cover 80.
If the sliding cover 80 slides relative to the main housing 70, the guiding protrusions 98 moves towards or away from each other, thereby elongating or shortening the tension spring 94. When the sliding module 90 with the sliding cover 80 slides in a slide range less than a length L1, the sliding module 90 creates an elastic force for closing the sliding cover 80 relative to the main housing 70. When the sliding module 90 with the sliding cover 80 slides in a slide range larger than the length L1 and less than a length L2, the sliding module 90 creates an elastic force for opening the sliding cover 80 relative to the main housing 70.
However, when each guiding protrusion 98 slides across a corner between the straight portion and the slanting portion of each sliding groove 77, the sliding cover 80 is slightly displaced with the guiding protrusion 98. Therefore, the sliding cover 80 does not slide smoothly relative to the main housing 70. In addition, the tension spring 94 is easily damaged when being frequently expanded by the guiding protrusions 98, thereby shortening the life span of the sliding mechanism.
What is needed, therefore, is a new slide mechanism which overcomes the above-described shortcomings.